package repositories

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"
	"thamanyah/cms/v2/internal/models"
)

type VideoRepository struct {
	SQLDB *sql.DB
}

var VideoRepo VideoRepository

// UpdateVideoOutcomeByJobID records what became of a transcoding job: the
// status it ended in, and the playback URL its output is served from. A job
// that failed has no output, so playbackURL is empty for those and the column
// is cleared along with the status. It returns ErrVideoNotFound when no video
// carries that job id, which the consumer treats as a message to drop rather
// than a fault.
//
// It returns the video it updated, carrying the members an announcement is
// built from — the row's id and title, and the names of the categories it is
// filed under. The consumer would otherwise have to read back what it just
// wrote, and reading it here keeps that SQL on this side of the seam.
func (svc VideoRepository) UpdateVideoOutcomeByJobID(ctx context.Context, jobID string, status models.VideoStatus, playbackURL string) (models.Video, error) {
	updated := models.Video{
		Status:            status,
		PlaybackURL:       playbackURL,
		MediaConvertJobID: jobID,
	}

	err := svc.SQLDB.QueryRowContext(ctx, `
		UPDATE videos
		SET status = $1, playback_url = $2, updated_at = now()
		WHERE mediaconvert_job_id = $3
		RETURNING id, title
	`, string(status), playbackURL, jobID).Scan(&updated.ID, &updated.Title)
	if errors.Is(err, sql.ErrNoRows) {
		return models.Video{}, ErrVideoNotFound
	}
	if err != nil {
		return models.Video{}, err
	}

	rows, err := svc.SQLDB.QueryContext(ctx, `
		SELECT c.name
		FROM video_categories vc
		JOIN categories c ON c.id = vc.category_id
		WHERE vc.video_id = $1
		ORDER BY c.name
	`, updated.ID)
	if err != nil {
		return models.Video{}, err
	}
	defer rows.Close()

	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			return models.Video{}, err
		}
		updated.CategoryNames = append(updated.CategoryNames, name)
	}

	return updated, rows.Err()
}

// GetVideoByID reads one video and the ids of the categories it is filed
// under. It returns ErrVideoNotFound when no video has that id.
func (svc VideoRepository) GetVideoByID(ctx context.Context, id string) (models.Video, error) {
	var v models.Video

	err := svc.SQLDB.QueryRowContext(ctx, `
		SELECT id, title, description, tags, file_name, storage_key, mediaconvert_job_id, status, playback_url, size_bytes, created_at, updated_at
		FROM videos
		WHERE id = $1
	`, id).Scan(&v.ID, &v.Title, &v.Description, &v.Tags, &v.FileName, &v.StorageKey,
		&v.MediaConvertJobID, &v.Status, &v.PlaybackURL, &v.SizeBytes, &v.CreatedAt, &v.UpdatedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return models.Video{}, ErrVideoNotFound
	}
	if err != nil {
		return models.Video{}, err
	}

	rows, err := svc.SQLDB.QueryContext(ctx,
		`SELECT category_id FROM video_categories WHERE video_id = $1 ORDER BY category_id`, v.ID)
	if err != nil {
		return models.Video{}, err
	}
	defer rows.Close()

	for rows.Next() {
		var categoryID int16
		if err := rows.Scan(&categoryID); err != nil {
			return models.Video{}, err
		}
		v.CategoryIDs = append(v.CategoryIDs, categoryID)
	}

	return v, rows.Err()
}

// VideoExistsWithStorageKey reports whether a video has already been
// registered under a storage key. It is served by videos_storage_key_key, the
// index Postgres builds for the column's UNIQUE constraint.
func (svc VideoRepository) VideoExistsWithStorageKey(ctx context.Context, storageKey string) (bool, error) {
	var exists bool
	err := svc.SQLDB.QueryRowContext(ctx,
		`SELECT EXISTS (SELECT 1 FROM videos WHERE storage_key = $1)`, storageKey).Scan(&exists)
	if err != nil {
		return false, err
	}
	return exists, nil
}

func (svc VideoRepository) CreateVideo(ctx context.Context, v models.Video) (models.Video, error) {
	tx, err := svc.SQLDB.BeginTx(ctx, nil)
	if err != nil {
		return models.Video{}, err
	}
	defer tx.Rollback()

	row := tx.QueryRowContext(ctx, `
		INSERT INTO videos (title, description, tags, file_name, storage_key, mediaconvert_job_id, status, size_bytes)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id, created_at, updated_at
	`, v.Title, v.Description, v.Tags, v.FileName, v.StorageKey, v.MediaConvertJobID, string(v.Status), v.SizeBytes)

	if err := row.Scan(&v.ID, &v.CreatedAt, &v.UpdatedAt); err != nil {
		return models.Video{}, err
	}

	rows := make([]string, 0, len(v.CategoryIDs))
	for _, categoryID := range v.CategoryIDs {
		rows = append(rows, fmt.Sprintf("($1, %d)", categoryID))
	}

	if _, err := tx.ExecContext(ctx, `INSERT INTO video_categories (video_id, category_id) VALUES `+strings.Join(rows, ", "), v.ID); err != nil {
		return models.Video{}, fmt.Errorf("linking categories %v: %w", v.CategoryIDs, err)
	}

	if err := tx.Commit(); err != nil {
		return models.Video{}, err
	}

	return v, nil
}